[jira] [Commented] (IOTDB-373) [Distributed] Query coordinating

["WangChao (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/IOTDB-373?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17080349#comment-17080349 ] 

WangChao commented on IOTDB-373:
--------------------------------

To check whether the node is busy, I think we have three methods:
 # only check cpu, memory, network, io usage
 # check cost of the working query plan and insert plan
 ## could be number of query plan, insert plan
 ## or the number of affected timeseries of the working query plan or insert plan
 # combine the above two

 

I think we could check node's total number of affected timeseries byt working plan to check whether it is busy.

 

 

 

> [Distributed] Query coordinating
> --------------------------------
>
>                 Key: IOTDB-373
>                 URL: https://issues.apache.org/jira/browse/IOTDB-373
>             Project: Apache IoTDB
>          Issue Type: Sub-task
>            Reporter: Tian Jiang
>            Priority: Major
>              Labels: distributed
>
> When using more than one replicas, query options are enriched and complicated. To ensure load balancing, we may have to choose the node with lowest load to perform the query, which requests knowing the load of each node and a formula to rank the nodes based on their status.
> We can also issue the same query to multiple replicas and pick up the fastest one to respond to the user as MapReduce has done. But this may result in resource wasting unless we feasibly support quick query cancellation.
> In a word, we should decide which replica(s) to serve a query and what information we need to collect to make the decision.



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